Earth boring under-reaming tool



Dec. 3, 1963 G. AMANN ETAL EARTH BORING UNDER-REAMING TOOL 5 Sheets-Sheet 1 Filed June, 1, 1960 1 mm -fii m Dec. 3, 1963 s. w. AMANN ETAL EARTH BORING UNDER-REAMING Tool.

3 Sheets-Sheet 3 Filed June 1, 1960 A TTORNE7 United States Patent 3,112,802 EARTH BGRENG UNDER-REAMING TOOL Gustav Wolfgang Arnann, Stoneleigh, Epsom, and Reginald .l'ohu Woolgar, Hayes, England, assiguors to Economic Foundations Limited, Hayes, England, a British company Filed June 1, 1969, Ser. No. 33,248 Claims priority, application Great Britain July 17, 1959 Claims. (Cl. 175-285) The present invention relates to an improved earthboring under-reaming tool suitable ifOl' use in underreaming or flaring out of the bottoms .of holes bored in the ground for the construction of concrete column foundations for buildings, retaining walls or other purposes.

According to the present invention an under-reaming tool comprises a generally cylindrical, hollow base for receiving spoil, the lower end of the base being adapted to permit the retention of spoil within the base, a superstructure rotatably mounted on the said base, a plurality 'f blades symmetrically disposed about the vertical axis or" the tool, a corresponding plurality of links pivotally connected by one end to a lower part of the superstructure and by the other end to the respective blades bet-ween the upper and lower ends thereof, the upper ends of the blades being pivotally connected to an upper part of the superstructure which is movable in a generally vertical direction relative to the lower part, whereby the blades are movable in generally vertical planes between a closed poistion in which the blades approach vertical orientation relatively close to the said vertical axis and an open position in which the blades are inclined with their lower ends relatively far from the said axis.

The superstructure may be mounted on the base by means of a thrust bearing, and may comprise a support member mounted on the base and an actuating member axially movable relative to the base and the support member. The superstructure may conveniently be of telescopic form, the support and actuating members being coaxial shafts, preferably of non-circular cross-section, sliding one within the other. The relative dimensions of the links and the blades, and the spacing of the pivots are preferably arranged to ensure that the lower end of the blade moves between the closed and open positions along a substantially horizontal path, since it is usually desirable for roles intended for concrete foundation columns to have horizontal bottoms.

Damping means, for example an hydraulic damping cylinder, may be provided between relatively movable moving 1 arts, for example between the actuating member and one of the links to limit the speed at which the blades move out to their open position. This prevents overfeeding of the blades during under-reaming which is liable to occur owing to the high eiliciency which tools according to the present invention can possess, and also prevents the blades from flying out quickly to the open position when the tool is lowered on to the surface of the ground.

It is advantageous for the blades to be formed with curved sheet wings to direct earth cut by the cutting edges into the base.

The bottom of the base is preferably formed by at least one hinged flap, with means for releasably retaining the flap or flaps in the closed position. increased economy of labour is attained if the fiaps are retained by quick-release and self-locking catches, for example by spring'loaded latch members.

Sometimes it is desired to clean up the bottom of the hole immediately before concreting, in order to remove small pieces of loose material that may have accumulated during under-reaming. For this purpose radial slots may 3,112,8h2 Patented Dec. 3, H253 ice be provided in the bottom flaps. Cleaning can be achieved by locking the thrust bearing by suitable means such as the insertion of a pin between the two halves of the bearing, so that the bottom portion of the tool will rotate with the whole tool. The slots will then act as cleaners by directing any loose material in the bottom of the hole into the base.

The invention will now be described by way of example with reference to the accompanying drawing, in which:

FIG. 1 is a side elevational view, partly in section, of an under-reaming tool according to the invention with the blades in the extended or open position,

FIG. 2 is a fragmentary cross-section of one blade along the line Ill-11 in FIG. 1,

FIG. 3 is a view similar to that of FIG. 1 but with the blades in the retracted or closed position,

FIG. 4 is a horizontal cross-section along the line IV-IV in FIG. 1,

\FIG. 5 is a horizontal cross-section along the line VV in FIG. 3, and

FIG. 5a is a fragmentary cross-section of a modification of the tool corresponding to a portion of the view shown in FIG. 5.

A shallow, hollow, cylindrical base 19' has a short central column 11 disposed axially within it and is connected to the column by stiffening members 12. The lower end of the base is provided with two semicircular flaps 13, hinged together by means of two radial pins 14 fixed between the sides of the base and the centr-al column along the common diameter of the flaps.

On the upper surface of each flap 13 near the mid-point of the arc is fixed an inverted hook l5, and springloaded, hooked, latch-members 16 are mounted on horizontal pivots on the inside of the cylindrical base to engage the inverted hooks and retain the flaps in a position Where they close the lower end of the base. Holes 17 provided in the cylindrical walls permit the release of the latches by the inseration of a bar to strike the tails of the latch members. The hinged edges of the flaps 13 are slightly bent in such a manner that when the flaps are released from the latches they cannot fail together into completely vertical positions, but remain downwardly divergent. This ensures that they can be readily closed and re-latched simply by lowering the tool on to the ground -or the bottom of a hole.

On the upper end of the central column 11 is a thrust bearing 18 incorporating a large brass washer 19, and the upper member of the bearing carries a support member in the form of vertical inner shaft 29 of square section. A central column 21 provided with upper and lower bearings extends upwards inside the inner shaft 2% and serves to maintain in a perpendicular disposition with respect to the base the superstructure which comprises the shafts 2i and 22 and head 23. Slidably mounted over the upper part of the inner shaft is a 'hollow outer shaft (also of square section) and serving as an actuating member. At the top of the shaft 22 is fixed a shallow head cylinder 23 of diameter equal to that of the base ill. The top of the outer shaft is also provided with means 24 for locking it to the lower end of a conventional kelly bar with a coupling box. Two heavy parallel pivot pins 23 are fixed symmetrically across the inside of the head cylinder, and on them are pivotally mounted two sheet steel wings or blades 26 stiffened with ribs 27 on their under sides, each wing having a straight leading edge extending normal to the pivot pin and a trailing edge curving from the other end of the pin to the outer end of the leading edge. The win s curve inwardly from the leading to the trailing edge, so that when the superstructure is rotated in the direction of the leading edge,

as shown by the arrows in FIG. 4, the curve of the wing directs the spoil towards the center of the tool and so into the base 1%. Parallel and near to the leading edge, each wing 26 is provided with a deep, inwardly directed stiffening rib 28, and an angle member 29 which is fixed between rib 23 and the leading edge of the wing and extends from the outer tip of the wing nearly as far as the pivot pin 25. To angle member 29, there is bolted a flat cutting blade 31, its outer edge providing a straight cutting edge which projects slightly beyond the leading edge of the wing. Holes 32 drilled in the wing along the line of the angle give access to the bolts holding the cutting blade, allowing easy replacement of the blade. The cutting blade is disposed approximately normal to the conical surface swept out by the cutting edge when the superstructure is rotated. At a point about halfway along the leading edge of the wing a heavy steel link-bar 33 is pivotally connected to the deep rib 23, and the other end of the bar is pivoted to the lower end of the inner shaft 20, immediately above the thrust hearing 13. The point of connection of the link-bar to tire wing is approximately equidistant from the tip of the wing, the pivot pin for that wing and the other pivot of the link bar. This condition ensures that the tip of the wing can move outwards along a substantially horizontal path.

A hydraulic ram is provided to serve as a damper, the upper end of the cylinder 34 of the ram being pivotally mounted near the upper end of the outer shaft 22, and the lower end of the piston rod 35 of the ram being pivotally mounted on the link-bar 33. Oil lines 36 recirculate the oil in the ram to a small reservoir 37 (shown only in FIG. 4) situated within the head cylinder, and a valve (not shown) in the return line serves to restrict the circulation of oil, adjustment of the valve thus permitting variation of the rate at which the link-bar 33 can pivot, and so of the rate at which the blades can be fed out to the open position.

In operation the tool is attached to the lower end of a conventional kelly bar by means of a coupling box connecting it to the uper end of the outer shaft 22 of the superstructure. The tool is thus suspended from the kelly bar, and the inner shaft 21 hangs in its lowest extended position with respect to the outer shaft (as in FIG. 3). The upper ends of the wings 26, being pivoted in the head cylinder 23, are drawn up and the tip of the wings 26 and of the blades 31 carried thereon are drawn in towards the vertical axis of the tool, that is into the closed position.

The tool is then lowered into a previously drilled cylindrical hole in the ground of corresponding diameter, and the rotation of the kelly bar is begun. When the base 10 of the tool reaches the bottom of the hole it rests thereon, and the superstructure of the tool rotates on the thrust bearing 13. It is an advantage of the tool according to the invention that the torque is transmitted directly from the kelly bar through the head cylinder to the blades. As the rotating kelly bar continues to be lowered, its weight presses on the outer shaft 22, together with additional thrust if the feeding of the kelly bar is powerassisted, depressing the upper ends of the wings and causing the tips of the blades to begin their outward movement towards the open position. As this movement progresses, the bottom of the hole is flared out into frustoconical form, the spoil being directed by the wings into the stationary hollow base It The movement of the wings is such that only the tip of the blades is at first effective, but subsequently more and more of the cutting edge becomes effective. This progressive action, together with the presence of the thrust bearing, is responsible for the high eifiiciency of the tool, and could in soft soils lead to an over-rapid feeding out of the blades were this not prevented by the hydraulic damper 34, 35. Within the limits imposed by the damper, the rate of cut is dependent upon, and can be controlled by, the rate of lowering of the ikelly bar. The conical flaring-out et the bottom of the hole is effected by progressive upward cutting, and the reaction of the earth on the blades thus assists in maintaining the tool in contact with the bottom of the hole. When the outer shaft 22 reaches its lowest position relative to the inner shaft 28, the upper ends of the wings 26 are fully depressed, and the blades reach their open position. The flaring-out of the bottom of the hole is then complete.

The kelly bar is then raised and the blades thereby drawn in to their closed position. When the outer shaft has reached the uper limit of its stroke, the whole tool is Withdrawn from the hole. The tool can then be swung to an unloading position over a spoil heap or earth-shifting vehicle, and the spoil discharged by striking the tails of the latch-members 16 through the holes 17 in the base cylinder 10, whereupon the hinged fiaps 13 fall open. When all the spoil has fallen out, the flaps can be closed by lowering the tool on to the ground, or lowering it once more into the hole, the divergent flaps being pressed to the closed position and there retained by the spring latches. If the tool is rested on the ground, the wings will be thrust out under the weight of the kelly bar, but this will not occur at dangerous speed owing to the speed limitation imposed by the hydraulic damper. When the tool is once more lifted, the wings will be drawn in, and the empty tool is ready for re-entry into the hole.

For storage or transport of the tool, a locking pin (not shown) can be inserted into corresponding holes 38 in the telescoping inner and outer shafts to retain the shafts in the extended position and hence to prevent the wings from moving outwards.

in a modification of the tool shown in FIGS. 15 the bottom flaps of the tool are provided with radial slots as shown at 39 in FIG. 5a. The thrust bearing by means of which the superstructure is supported on the base 19 of the tool can be locked by the insertion of a pin (not shown) between the two halves of the bearing, whereupon the base It can be rotated with the whole tool, the slots 39 acting as cleaners to direct loose material into the base as described above.

What is claimed is:

1. In an earth-boring under-reaming tool, having a cylindrical hollow base for receiving spoil, a superstructure including an upstanding support member mounted on said base and an actuating member rotatable with and slidable longitudinally of said support member, a plurality of blades symmetrically disposed about and pivotally supported at one end thereof to said superstructure and links for each blade pivotally connected to a respective blade and to said superstructure, the improvement which comprises means mounting the support member rotatably on the base whereby said superstructure can rotate relative to said base when the base is stationary at the bottom of a hole to be under-reamed.

2. An earth boring tool for under-reaming a bore formed in the ground, the tool comprising a cylindrical hollow base adapted for receiving spoil caused by the under-reaming operation, a superstructure constituted by first and second telescoping members, means rotatably supporting one of the telescoping members on the base, the other of the members being adapted for telescoping axially of the first said member towards and away from the base, a plurality of blades each adapted for performing a cutting function to enable under-reaming of the ground, means respectively connecting each of said blades to both telescoping members such that said blades are caused to move respectively between extended and retracted position and said other telescoping member is moved towards and away from said base, said blades rotating as said first member is caused to rotate and while said base is supported in stationary manner in said bore, whereupon movement of said other telescopic member towards said base causes extension of said blades and consequent under-rowing of the ground around said bore.

3. An earth boring under-reaming tool comprising: a cylindrical hollow base adapted to receive spoil, a superstructure including lower and upper portions, said lower portion being upstanding, means rotatably supporting said lower portion on said base whereby said superstructure can rotate relatively to said base when said base is supported in stationary manner within a hole to be underreamed, said upper portion being supported on said lower portion so as to be slidable longitudially of said lower portion between upper and lower positions, a plurality of blades symmetrically disposed with respect to a vertical axis through the superstructure each blade being pivotally connected to the upper portion of said superstructure, a link for each of the blades, each link having one end pivotally connected to a respective blade and another end pivotally connected to said lower portion so that upon movement of said upper portion between said upper and lower positions said blades are caused to respectively move between retracted and extended positions, said blades in the extended position being adapted to under ream the hole when the superstructure is caused to rotate.

4. A tool according to claim 3 in which the links fold upon upward movement of the upper portion, each of the blades having a lower end which moves in a substantially horizontal plane with said upper portion being vertically displaced.

5. A tool according to claim 3 wherein the lower and upper portions are coaxial shafts of non-circular crosssection, sliding one within the other.

6. A tool according to claim 5 comprising a shallow cylindrical head having a diameter equal to that of said base, said head being supported on said upper portion.

7. A tool according to claim 3 comprising at least one hinged flap at the bottom of said base and spring loaded latch means for releasably retaining said flap in a closed position.

8. A tool according to claim 7 wherein radial slots are provided in the bottom flap and comprising means for locking the superstructure to the base so that the base can rotate with the superstructure.

9. A tool according to claim 3 comprising damping means coupled to said upper portion and operatively associated with said blades to damp movement of said blades from the retracted to the extended position.

10. A tool according to claim 9 wherein said damping means comprises a dam-ping cylinder coupled to the upper portion and at least one of said links.

References Cited in the file of this patent UNITED STATES PATENTS 1,406,348 Corrigan Feb. 14, 1922 1,787,001 Hunt et a1 Dec. 30, 1930 2,031,353 Woodruff Feb. 18, 1936 2,203,246 Zum-Berge June 4, 1940 2,719,698 Darin et a1. Oct. 4, 1955 2,910,274 Scott Oct. 27, 1959 FOREIGN PATENTS 160,770 Australia Jan. 26, 1955 551,838 Germany June 4, 1932 835,919 Great Britain May 25, 1960 

1. IN AN EARTH-BORING UNDER-REAMING TOOL, HAVING A CYLINDRICAL HOLLOW BASE FOR RECEIVING SPOIL, A SUPERSTRUCTURE INCLUDING AN UPSTANDING SUPPORT MEMBER MOUNTED ON SAID BASE AND AN ACTUATING MEMBER ROTATABLE WITH AND SLIDABLE LONGITUDINALLY OF SAID SUPPORT MEMBER, A PLURALITY OF BLADES SYMMETRICALLY DISPOSED ABOUT AND PIVOTALLY SUPPORTED AT ONE END THEREOF TO SAID SUPERSTRUCTURE AND LINKS FOR EACH BLADE PIVOTALLY CONNECTED TO A RESPECTIVE BLADE AND TO SAID SUPERSTRUCTURE, THE IMPROVEMENT WHICH COMPRISES MEANS MOUNTING THE SUPPORT MEMBER ROTATABLY ON THE BASE WHEREBY SAID SUPERSTRUCTURE CAN ROTATE RELATIVE TO SAID BASE WHEN THE BASE IS STATIONARY AT THE BOTTOM OF A HOLE TO BE UNDER-REAMED. 